Long-term persistence of cellular immunity to Oka vaccine virus induced by pernasal co-administration with Escherichia coli enterotoxin in mice.

A mutant of Escherichia coli enterotoxin induced cellular immunity to a live varicella vaccine (the Oka strain) as a mucosal adjuvant in mice. The persistence of this cellular immunity was investigated. A commercially available live Oka vaccine virus and toxin were administered once simultaneously via the nasal route, in mice. Ten or 12 months later, a delayed-type hypersensitivity to the vaccine virus was detected by footpad test, but an antibody neutralizing the varicella-zoster virus was not. When spleen cells from mice immunized with the vaccine and toxin were re-stimulated by live vaccine in vitro, their thymidine uptake and IL-2 production were higher than those from mice immunized with the vaccine alone, but lower than those of spleen cells prepared from mice 2 months after nasal administration. Production of IL-4 in these cells, however, was not induced by re-stimulation in vitro. These results suggest that although humoral immunity for Oka vaccine virus is only weakly induced by one co-administration of the vaccine and toxin, cellular immunity is induced and maintained over 1 year, though it declines with age. The nasal administration of the vaccine and toxin might be effective for maintaining cellular immunity to the varicella-zoster virus long term.